A ball pin with these design features corresponds to the state of the art as put into practice in universal joints with high load-bearing capacity in chassis of motor vehicles. Such a ball pin has been manufactured in very large numbers by the corresponding manufacturers during the past decades. They are manufactured in one piece by machining an optionally preformed blank. Thus, different pin sizes require different blanks and correspondingly different machine control programs for machining in series production. The notch effect on the surface of the neck of the pin stump at its undercut transition into the joint ball, which is generated by the machining, causes a special problem, because the permanent load-bearing capacity is considerably reduced as a result. It is also difficult to meet high requirements in terms of corrosion protection, especially at the neck of the pin stump, at its transition into the joint ball. This corrosion protection is partially ensured by a very expensive process in the prior-art ball pins, of which millions of pieces are manufactured.
French Patent No. FR-PS 1,089,717 discloses a universal joint designed for a special application, in which the joint ball with an inner cone of a through-hole is axially pressed onto an outer cone of a fastening pin on a pin stump by a threaded screw. A very similar connection of a joint ball to a pin stump has also been known from British Patent No. GB-PS 1,020,671 for a joint of a relatively large size. Such ball pin designs are expensive and are equally poorly suitable for large lots for use in heavily loaded ball joints as for the transmission of stronger rotating forces between the joint ball and the pin stump.
The fastening of a joint ball made of plastic on a cylindrically designed ball pin made of steel for ball joints or the like carrying low loads has been known from German Auslegeschrift No. DE-AS 11,05,292. German Utility Patent No. DE-GM 17,08,040 discloses a mounting of spherical control pins, in which a spherical head part is prepared separately from a hard material, and it is attached to a pin made of a tough, elastic material with a blind hole.